John Smith wrote:
Michael Coslo wrote:


Let's not forget the possibility that they didn't know how to model
the thing. I'm no great shakes at modeling, and that antenna is beyond
my prowess at the present.

Of course, I'm mpore likely to assume that discrepancies between
computer world and reality are my fault. Some others might assume that
the data they input was correct, so it must be the programs fault....

And some on the fringe might say the antenna CAN't work - the computer
says it can't!

- 73 de Mike N3LI -

Absolutely, I am NOT making any statement "they" are correct (I have
never tried this antenna myself--either as a model or as an actual
antenna in reality.)

But, anyway you cut it, and on the ground floor, there ARE discrepancies
in the basic equations, formulas and assumptions being put to use in the
NEC, someday these will be fleshed out ...

Regards,
JS

I doubt that any antenna an amateur is likely to build has some physics
not adequately modeled by the math in NEC. Exactly what might be these
discrepancies in equations, formulae and assumptions? Considering that
NEC has had decades of validation against actual measurements and a lot
of really, really smart people looking at how it works, I'd be kind of
surprised.

However, I can also easily believe that an amateur (or professional)
could build an antenna that has measured performance different than
expected from their NEC model of that antenna. The differences would
lie, most likely, in these areas:
1) Inaccuracies in the model itself. Things like earth properties (NEC
assumes uniform dielectric, it isn't) are an important source of error
for antennas close to the ground. Most amateur models do not include a
very good model of the surroundings (supports, trees, feedlines, etc.)

2) Inaccuracies in the measurements or not measuring the right things. A
good example is using NEC to get feedpoint characteristics, then
measuring at the rig, and not properly accounting for the transmission
line, particularly if the feedpoint Z is reactive.

In the professional antenna world, if someone models an antenna, then
builds it and tests it on the range, and the measurements differ from
what the model predicted, the usual assumption is that what was built
differed from what was modeled, or the measurements were off.

Jim Lux wrote:
John Smith wrote:
[A bunch of chit Jim, obviously, will/and does differ with]
Regards,
JS



I doubt that any antenna an amateur is likely to build has some physics
not adequately modeled by the math in NEC. Exactly what might be these
discrepancies in equations, formulae and assumptions? Considering that
NEC has had decades of validation against actual measurements and a lot
of really, really smart people looking at how it works, I'd be kind of
surprised.

I don't believe the above it correct. Indeed, if you will only review
my past objections and reflections on how "the NEC engine" demonstrates
"differences" you will be focused at the "focal point" of my "inquiries" ...


However, I can also easily believe that an amateur (or professional)
could build an antenna that has measured performance different than
expected from their NEC model of that antenna. The differences would
lie, most likely, in these areas:

Look, the dipole, standard monopole (1/4, 1/2, longwire, etc.) is NOT in
debate. Indeed, it is like NEC was designed to "explain/model" these, DUH!

1) Inaccuracies in the model itself. Things like earth properties (NEC
assumes uniform dielectric, it isn't) are an important source of error
for antennas close to the ground. Most amateur models do not include a
very good model of the surroundings (supports, trees, feedlines, etc.)

2) Inaccuracies in the measurements or not measuring the right things. A
good example is using NEC to get feedpoint characteristics, then
measuring at the rig, and not properly accounting for the transmission
line, particularly if the feedpoint Z is reactive.

In the professional antenna world, if someone models an antenna, then
builds it and tests it on the range, and the measurements differ from
what the model predicted, the usual assumption is that what was built
differed from what was modeled, or the measurements were off.

I could pick apart the above, attempt to poke fun, etc. -- however, I
would much rather join forces and attempt to focus on the points which
would lead us to real answers -- i.e., the arrl and illiterates have
already done enough damage, let us pursue a more productive path?

Leave us leave our minds open, OK?

Regards,
JS

John Smith wrote:

...
Leave us leave our minds open, OK?

Regards,
JS


And damn, and DAMN, and well DAMN ...

If you want to build something from a 19?? to 1950 (or beyond?)
publications, do I stop you? Is this what "you have you back up your
ego about?" It this what threatens you? If so, go ahead, go to your
grave with your pursuits, without my critique! ...

I am here about what "I AM", about "WHAT I THINK", about "WHAT I SEE",
about "WHAT I SUSPECT", about "WHAT I WONDER", about "MY QUESTIONS TO
OTHER MEN/WOMEN", about what I simply want to think about and want
answers to ... yanno, I think you are really endangerd by those "others"
here, I find ... Cecil, where are you? evil grin

If you can't participate, if you think I am am an idiot, if you think I
am a moron ... could you do it politely until I give you reason to do
differently ... indeed, I may feel threaten my "moronic brains" and
respond ... please don't take insult, just reassure me I am not wrong ...

Regards,
JS

John Smith wrote:

...
If you can't participate, if you think I am am an idiot, if you think I
am a moron ... could you do it politely until I give you reason to do
differently ... indeed, I may feel threaten my "moronic brains" and
respond ... please don't take insult, just reassure me I am not wrong ...

Regards,
JS

Look, that got "corrupted" in my frustration, I am not a writer, I just
attempt to bring my skills up to speed to participate here ...

Let me change all that:

If I can't think here ... If I can use this as a "note pad" ... If I can
speculate here ... If I can't search for others here, if I can't use
other as a "backboard" here ...

.... then let it all be damned ... I am an idiot ... and let's look over
your past, present and future questions, speculations, advances, etc. ...

Regards,
JS

John Smith wrote:

...
Regards,
JS

Geesh, can = can't in a lot of that. Those with a brain will know ...
those without will point it out ... don't think it necessary ... PLEASE!

I am taking a break from all this ... I need to ... :-)

Regards,
JS

On Thu, 02 Oct 2008 15:10:05 -0700, John Smith
wrote:

Geesh, can = can't in a lot of that. Those with a brain will know ...
those without will point it out

It took 3 posts to point it out, but you managed....

... don't think it necessary ... PLEASE!

Not in the least necessary from any perspective; but I can see why
some modeling would be impossible to confirm against the data offered.
Afterall, if the prognosis of, say, netzheimers were based on a ±0.1dB
DNA error, then all bets are off in proving sanity.

Knowledge may give weight, but accomplishments
give lustre, and many more people see than weigh.
Lord Chesterfield

73's
Richard Clark, KB7QHC

Richard Clark wrote:

...
Not in the least necessary from any perspective; but I can see why
some modeling would be impossible to confirm against the data offered.
Afterall, if the prognosis of, say, netzheimers were based on a ±0.1dB
DNA error, then all bets are off in proving sanity.

Knowledge may give weight, but accomplishments
give lustre, and many more people see than weigh.
Lord Chesterfield

73's
Richard Clark, KB7QHC

LOL!

Thanks Richard!

I will place a grain (or two, or more) of salt upon the joint of the
thumb with wrist (and, thinking fondly of you, as reason enough), swag
down the shot of Tequila and touch tongue to the joint ... but for now,
more important things beckon me ...

Ahh yes, if only for a night ... I suppose you will be here tomorrow ...
may your dreams be filled with the such of mine ... here is too our
further "exploits" :-)

Regards,
JS

John Smith wrote:
I don't believe the above is correct.

Proof that NEC cannot model everything is at:

http://www.w5dxp.com/SUPRGAIN.EZ

Would you believe a vertical with
24 dBi omnidirectional gain?
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein

Cecil Moore wrote:

...
Would you believe a vertical with
24 dBi omnidirectional gain?

Cecil:

With the "truth" we have maintained before us, and especially here,
another shot of Ta-Kill-Ya (or, Tequila), I'd believe anything you would
state!--await my returned "brain" tomorrow--please? ROFLOL

Regards my friend,
JS

John Smith wrote:
--await my returned "brain" tomorrow--please? ROFLOL

Good luck on that one. :-)
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein